I'm wondering, would it be possible for sesi to implement this in future versions?

You mean rendering subd surfaces with crease weights? If it's that, then no, due to patent issues.

Mmm, no, I don't think that's it edward. If you apply a Subdivide SOP to a model you'll notice it has that ‘Smooth Vertex Attributes’ checkbox. Basically it prevents textures from bunching up and being distorted in areas where your topology is not perfectly mesh like (5-sided polys, few too many edges coming together at one point, etc). Like so…



The problem is that you can't have vertex smoothing when rendering as subdivision surfaces. You can feed a manually subdivided version of the model into a Smooth SOP, and then render that as SubDs, but that kinda defeats the purpose, especially since you need a few iterations to get accurate results.

hey DJ, did you ever figure this out? I also discovered that the uv mapping you see in the viewport / with subd sop on is different than when rendering as subd…

Peter

Vertex attribute smoothing will be supported in the next version of Houdini.

Andrew

Hi Andrew, so I take it that getting the uv textures to behave as they do with a subd sop is not possible? If the uv mapping done on low poly mesh, with the subd sop for checking while working, then switching over to render with the ‘render as subd’ switched on (and the subd sop disabled) the textures will ‘slide’ and not line up as they did when checking/rendering thru the subd sop?

Hope this question makes sense… Just trying to learn the workflow in houdini… a shame to spend hours uv mapping and then pressing render and seeing all your seams slide all over.

Peter

If you are using smoothed vertex attributes on the subdivide SOP, then yes, the rendered result will not match up. Rendering as subdivision surfaces currently operates the same way as using the subdivide SOP without vertex attribute smoothing, which will give you a result similar to (4) in DaJuice's post. The only way to get the smooth interpolation behavior in mantra is by using point attributes instead of vertex attributes.

Andrew

so you mean doing your uv mapping in vertex attributes, and promoting that to point uv attributes? That has so far given me very bad results.

Is there a way to uv map low polys so that what you see in the viewport is what is going to be renderer by the ‘render as subd’ option?

Sorry for being so daft guys,… but I fail to understand the reason behind having an option of ‘render as subd’ if it does deal with the textures properly. Most of the stuff that has to be subd'd is low poly meshes with uv textures hand applied… am I missing something here..? ops:

Peter

priel
so you mean doing your uv mapping in vertex attributes, and promoting that to point uv attributes? That has so far given me very bad results.

Is there a way to uv map low polys so that what you see in the viewport is what is going to be renderer by the ‘render as subd’ option?

Sorry for being so daft guys,… but I fail to understand the reason behind having an option of ‘render as subd’ if it does deal with the textures properly. Most of the stuff that has to be subd'd is low poly meshes with uv textures hand applied… am I missing something here..? ops:

The “Render As Subdvision Surfaces” option currently is really nice if you are using point based UVs or are doing your shading procedurally with “P” or something. But as you noticed Render as Subs and vertex uvs are a problem. Its fixed in Houdini 9, but until then you'll have to resort of render straight polygons that have been subdivided with the Subdivide SOP or promote the vertex uv attribs to point and clean/tweak them.

Hi wolfwood, ya I've given up on getting the uv & ‘render as subd’ working. But now I seem to have a similar problem when using the subd sop… argh.

I've been trying to make this work the whole day.. but the more I try the more confused I get.. I'll give you a quick example:

Create a tube sop (Polys, quadrilaterals, y axis, height:5, 4 rows, 10 columns)

Add an edit sop (select the inner edge loops and scale or move them up respectively down to the tubes end loops, so the tube will have hard edges when subd comes on.. not that it matter with this geometry..but anyway)

Add a uvproject ( vertices, cylindrical & press initialize)

Add a subd sop (depth 2)

Add a shader with a checker material or something.

Now look at the tube, there is a seam which is warped. If you go to the uv view and check the layout with the subd sop viewable you also see that the mesh is smoothed at that ‘seam" as well. If ’smooth vertex attrib' is checked off, the mesh goes back to a more predictable form, but alas the uv mapping is gone bonkers as when using the ‘render as subd’ does.

So… how do I get this to work? shouldn't the subd sop be able to subdivide the low poly mesh and keep the UV mapping locked on its surface?

Peter

attached are two screen shots from the above example… one with the uv projection set to vertex and another to points.